Elenco 130-in-1 Electronics Playground - Manual (Page 148)

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If you use a meter you can find the exact value of a
resistance; but when you only want to know
approximate resistance values, you can use this
resistance tester.
This circuit converts resistance to electric current and
compares it with the comparator’s reference current
to tell you the approximate range of resistance. The
comparator has a reference voltage of about 0.82V.
Build the circuit and set the switch to position A.
Connect the material to be tested between terminals
13 and 14. The LED lights if the resistance is less
than 100k
Ω, otherwise it is off. If the LED lights,
connect terminals 93 and 86. If the LED turns off now
the resistance is between 10
Ω and 100kΩ
k . If it stays
on, remove the wire from terminal 86 and connect it
to terminal 84. If the LED turns off now, the
resistance is in the range of 1 to 10k
Ω
k k . If the LED still
doesn’t turn off, remove the wire from terminal 84
and connect it to terminal 76. If the LED turns off
now, it means that the resistance is in the range of
100
Ω to 1kΩ
k k ; if it stays on, the resistance is less than
100
Ω.
Notes:
EXPERIMENT #126: RESISTANCE TESTER
Schematic
Wiring Sequence:
13-93-69-WIRE
14-79-70-121
75-83-94-90-88-31-63-131
33-67
68-80-87
85-89
119-124
122-132